It is customary to provide a radiator grille cover to lessen the cooling action of a radiator in the winter. These grille covers, commonly referred to as "winterfronts", are broadly characterized by being connected to the front or exterior surface of the grille and are made up of one or more adjustable flaps secured in place by snap fasteners so as to enable the flap or flaps to be opened by varying degrees in order to control the effective opening size for the passage of air through the radiator grille according to the temperature level. For example, U.S. Pat. No. 1,602,801 to W. D. Walker discloses such a radiator cover in which the opening size is adjustably controlled by a combination of snap fasteners and slide-type fasteners. In U.S. Pat. No. 2,020,838 to H. E. Kaemmer, a grille cover is composed of fabric material and has a plurality of flaps which can be folded away from respective openings to control the total opening size through the cover. A similar approach is taken in U.S. Pat. No. 2,070,919 to J. P. Posey but again relies upon flap sections which can be folded or doubled back upon themselves to adjust the effective opening size.
In U.S. Pat. No. 1,407,216 to L. D. Potter, an adjustable center opening is formed by an iris-type closure being controlled in size by a pinion which intermeshingly engages with a curved rack and operated to cause swinging movement of the segments making up the adjustable closure. In U.S. Pat. No. 4,236,592 to J. H. Ziegler and assigned to the assignee of the instant invention, a winterfront is used in combination with an air deflector and includes flaps which can be doubled upon themselves to adjust the effective opening size for passage of air through the grille into the radiator and engine section of the automobile. In U.S. Pat. No. 4,523,657 to T. A. Kooyumjian, a plurality of flap sections are arranged in quadrants with the common central portion formed between the flap sections defining an opening for the admission of air into the radiator section and which opening size can be regulated by folding the quadrants away from the center opening.
The use of flat panel sections with flap sections as disclosed in the patent to Kooyumjian is desirable from the standpoint of simplicity of construction and reduced size. However, when the opening size is regulated by the degree of fold or doubling over of the flap sections upon themselves, the flap sections are subject to being accidentally released and may interrupt the movement of any substantial amount of air through the center opening. Thus, it is important that the flap sections surrounding the opening be adjustable in such a way as to be either completely removed or foldable into a position in which they are not exposed and cannot be accidentally released.